The present invention relates to systems for constructing spatial structures.
Presently, the assessment of loads, the distribution of stresses or forces, moment losses and the obtention of the maximum advantage of the material used, are the trends demanded or required by architects and engineers. At the same time, these requirements have resulted in a new method of construction, known as spatial structure. In this new shape and size architecture, technical advantages and architectural beauty are in close harmony. Up to a certain point the spatial structure can be considered as an extension into space of the conventional frame structure systems, in which the lines of action of the stresses are coplanar, while in spatial structures the lines of action of the stresses are branched outwardly into space. In spatial structures, the tensions or stresses on the various struts or tubes are largely uniform, without one thereof being overloaded, the structure thus having a great resistance to outer stresses. The inner tensions or stresses diminish, thus the necessary sections of the drawn or compressed elements also diminish, which results in a remarkable decrease in the amount of necessary material.
Furthermore, there are other factors which lead to greater economy and which justify the growing use of spatial structures. Such factors are: prefabrication of the essential elements, their standardization and savings in labor.
For example, spatial structure concepts have been used in domes or arches which cover a space of 200 meters without the use of intermediate columns. Presently, projects which contemplate the covering of surfaces up to 400 meters in diameter are being studied.
A comparison of weights between a spatial structure and a lineal bearing element structure would, in principle and on an approximate basis, result in a weight of 30 to 50% for a spatial structure having a distance of up to 50 meters between the supports, in comparison with a comparable lineal structure.
In the field of spatial structures and in order to achieve the objects of the invention the following concepts were fundamentally taken into account:
(A) Structural system whose main feature is its high degree of hyperstaticity.
(b) The use of soldered or welded nuclei for two layers spatial structures is only profitable with a distance of 40 meters between the supports. However, and even from these distances, a screw bearing an axial load cannot be replaced during assembly, since the structure is successfully positioned only with the help of a screwdriver. These conclusions were reached after various trials and experiments.
In order to meet these requirements the following should be fulfilled:
(1) Connection or coupling by means of screws or bolts.
(2) Surveying nucleus.
(3) Transmission of tensions or stresses from the tubes to the axially shaped nucleus.